1. Field of the Invention
The present invention relates to a lock. In particular, the present invention relates to a lock with a clutch function, allowing free rotation of the outer handle when the lock is in a locked state.
2. Description of the Related Art
U.S. Pat. No. 4,583,382 discloses a door lock with a reversible latch assembly with integrated function. The door lock comprises a generally rectangular case, a latch bolt disposed in the case, and a dead bolt disposed in the case. The case includes a front plate for confronting a door frame. A portion of the latch bolt is selectively extensible from the front plate of the case for securing relative movement between the door and the door frame. A portion of the dead bolt is selectively extensible from the front plate of the case for further securing relative movement between the door and the door frame. An outside handle is provided on the outside of a side of the case for selectively retracting the latch bolt disposed on. An inner handle is disposed on the inside of the case of simultaneously retracting the latch bolt and the dead bolt.
A stop works catch is provided within the case for securing at least one of the inside handle and the outside handle against operation. A thumb turn is operable from the inside of the door for selectively releasing the stop works catch and retracting the dead bolt in a first position, deploying the stop works catch in a second position and deploying the stop works catch and extending the dead bolt in a third position. A lock core is operable from the outside side of the door for selectively retracting the latch bolt and the dead bolt. When the dead bolt is extended, operation of the lock core is prevented. The door lock further includes an inner and an outer retractor hub means which are axially aligned and mounted for independent rotation within the case. The inner retractor hub means is located adjacent to the inner side of the case and operated by the inside handle. The outer retractor hub means is located adjacent to the outside side of the case and operated by the outside handle.
The stop works catch is provided with a recess which cooperates with a projection on the outer retractor hub means to prevent rotation of the outer retractor hub means. Thus, the outside handle could not be turned when in a locked state. However, the internal parts of the door lock could be damaged if the outside handle is frequently depressed when the user is not aware of the locking state of the lock. Also, the internal parts of the door lock could be damaged if the outside handle is depressed with a relatively large force when the user is not aware of the locking state of the lock. The life of the door lock is shortened.